"Right now he's out for this week, and that's really what we're focused on," coach Mike McCarthy said Monday.
Matthews underwent right thumb surgery prior to Week 17. It was the second time this season that Matthews required thumb surgery. The first time it happened, on Oct. 6, Matthews suffered a Bennett's fracture and missed the next four games after surgery.
Matthews has not been available to media and it's unknown whether his latest injury was also a Bennett's fracture. But the Packers know they'll have to beat the San Francisco 49ers in the wild-card round of the playoffs without their sack leader.
"I really don't have a feel for Clay, as far as where he is," McCarthy said. "I really haven't even seen him to talk to him. You're always cautious with players after surgery. That's why he didn't travel with the team (to Chicago for the regular-season finale)."
When Matthews returned earlier this season after a month-long absence, he wore a giant club over his right hand for one game. For a pass-rusher who is so reliant on the use of his hands, Matthews didn't do well with the club, recording a season-low two tackles and adding no sacks in a Week 10 loss to the Philadelphia Eagles.
A week later, Matthews switched to a cast, one that allowed his fingers to be free. Matthews' performance improved, racking up three sacks over the subsequent two games. It was while wearing that cast, though, that he suffered a "repeat injury" on Dec. 22.
Without Matthews, whose 7.5 sacks this season is the second-lowest mark of his five-year career, Green Bay will need a collection of other defensive players to put pressure on San Francisco quarterback Colin Kaepernick in Sunday's matchup.
Defensive lineman Mike Daniels is second on the team with 6.5 sacks this season, followed by linebackers Mike Neal and A.J. Hawk, both of whom have 5.0 sacks.
When the Packers and 49ers met in Week 1 this season, Matthews tackled Kaepernick out of bounds and drew a 15-yard, personal-foul penalty. That began a sideline scuffle in which Matthews got mixed up with San Francisco offensive lineman Joe Staley. A day later, 49ers coach Jim Harbaugh took a verbal shot at Matthews, telling reporters, "I think that young man works very hard on being a tough guy. He'll have some repairing to do to his image after the slap (to Staley)."
Matthews responded later that week, saying, "I'm an awesome player, not a dirty player."
Well, in the rematch between the two teams, Matthews will be an inactive player.